Electric translating circuits



Jan. 9, 1934. R NZ 1,943,126

ELECTRIC TRANSLAT ING C IRCUITS Filed May 5, 1932 Fig.2.

Inventor: Paul Lenz,

His Attorneg.

Patented Jal 9, 1934 UNITED STATES PATENT ()FFICE ELECTRIC TRANSLATING CIRCUITS Paul Lenz, Berlin-Grunewald, Germany, assignor to General Electric Company, a corporation of New York Application May 3, 1932, Serial No. 609,005, and in Germany May 20, 1931 Claims.

My invention relates to electric translating circuits an' more particularly to such circuits in cluding an electric valve for controlling or regulating an electrical condition of the circuit.

5 In the operation of electric translating circuits including electric valves provided with thermionic cathodes, it is customary to provide an independent heating circuit for the heating elements of the valves, the heating elements comprising either filamentary cathodes for the valves or sources of heat for separate cathode members. When a filamentary heating element comprises the cathode itself, the load current is so distributed through the filament as to constitute approximately the equivalent of half the load current flowing through the complete length of the filament, thus providing an additional source of heat energy for the cathode. In the case of electric valves operating on the principle of vapor ionization, whether of the filamentary cathode or indirectly heated cathode type, there also occurs a certain amount of positive ion bombardment of the cathode as well as a certain amount of conduction of heat from the arc stream, which factors also tend to raise the cathode temperature.

All of the factors above noted tend to raise the temperature of the cathode with an increase in the load current. For the most satisfactory operating conditions, however, it is preferable that the electric valve should operate at a substantially constant cathode temperature. My invention relates more particularly to a new and. improved arrangement for maintaining constant the cathode temperature of an electric valve connected in an electric translating circuit subject to variable load conditions.

It is an object of my invention therefore to provide new and improved electric translating circuit including an electric valve provided with a thermionic cathode which will overcome the above mentioned disadvantages of the arrangements of the prior art, and which will maintain the cathode of the valve at substantially constant operating temperature.

It is another object of my invention to provide an improved electric translating circuit including an electric valve provided with a thermionic cathode in which the energization of the cathode is varied inversely in accordance with the load current transmitted through the valve.

In accordance with my invention a source of current is interconnected with the load circuit through an electric valve provided with a thermionic cathode, and there are provided means 55 including a variable impedance device for varying the energization of the load circuit; that is, the current transmitted through the valve. There also provided a variable impedance device in the heating circuit of the thermionic cathode and means for simultaneously varying the impedances of the two impedance devices to maintain the temperature of the thermionic cathodes substantially constant.

For a tter understanding of my invention, together .th other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims. Fig. 1 of the drawing illu trates an arrangement embodying my invention in which the control of the energization of the load circuit is effected by means of a variable impedance in the grid circuit of the electric valve, while Fig. 2 shows a modification of my invention in which the energization of the load circuit is controlled by a variable impedance connected directly in series with the load.

Referring now to Fig. 1 of the drawing, there is illustrated an arrangement for energizing a load device 10 from a source of alternating current 11 through an electric valve 12. The elec tric valve 12 may be either of the high vacuum pure electron discharge type or he vapor electric discharge type and is provided with an anode, a cathode, and a control grid. The cathode is illustrated as of the directly heated filamentary type, although it will be obvious to those skilled in the art that a valve of the indirectly heated cathode type may be employed if desired. The cathode of the valve 12 is provided with a heating circuit comprising a filament transformer 13 energized from the alternating current source 11 through a variable impedance device illustrated as a variable resistor 14. In order to control the energization of the load device 10 the grid of the 95 electric valve 12 is excited from an impedance phase shifting circuit comprising a transformer 15 connected across the alternating current source 11 and a. capacitor 16 and variable resistor 17 serially connected across the secondary winding of the transformer 15. As is well understood by those skilled in the art, the grid potential will be obtained between the electrical midpoint of the secondary winding of the transformer 15 and the junction between capacitor 16 and variable resistor 17. A member 18 provided with two insulated contacts is provided for simultaneously varying the resistances of the devices 14 and. 17 in an opposite sense.

It will be well understood by those skilled in the art that the energization of the load device 10 may be controlled by varying -he resistor 17 and thus the phase of the potential applied to the control grid of the valve 12 with respect to its anode potential; for example, by decreasing the setting of the variable resistor 17, the potential applied to the grid of the valve 12 will be advanced in phase, thus increasing the energization of the load device 10, and vice versa. It will be noted. however that, as the member 18 is operated to decrease the resistance of th device 17 and to increase the energiza icn of the load device 10, With a resultant increase in the heating of the cathode of the valve 12 occasioned by the several factors noted above, the setting of the variable resistor 14 is simultaneously increased, thus decreasing the heating current supplied by the filament transformer 13. By properly proportioning the resistors i i and l? for the particular characteristics or" the val be controlled, the heating current supplied by former 13 may be varied in a 2 i In Fig. 2 there ShOWl'l invention in which the control of the tion of the load device 10 is erlectec a variable impedance 6 variable resistor 19 connectec in load device 10. A member 26 simultaneously varying settin, resistors la and 19. With this arranger To,

c as the energization of the load device 10 is increased by decreasing the setting of the variable resistor 19 the setting of variable """"tor 1a is simultaneously increased to decrease the rent supplied to the cathode of the electric valve 12, and vice versa. In this manner substantially constant cathode temperature may be maintained as in the arrangement of 1.

While I have described what I at present consider preferred embodiments of invention, it Will be obvious to those skilled the that various changes and inodificatio 5 may be made Without departing from my in ention, and Z therefore aim in the appended claims uo cover all such changes and modifications as fall within the true spirit and scope or" n w invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric translating circuit comprising a source of current, an electric valve provided with a thermionic cathode, a heating circuit for said cathode, a load circuit connected to said source through said valve, means including a Variable impedance device for controlling the current transmitted through said valve, a variable impedance device for controlling the energization of said heating circuit, and means for simultaneously varying the impedances of said devices to maintain the temperature of said thermionic cathode substantially constant.

2. An electric translating circuit comprising a source of alternating current, an electric valve provided with a control grid and a thermionic cathode, a heating circuit for said cathode, a. load circuit connected to said source through said valve, means including a variable impedance device for controlling the potential of said control grid, a variable impedance device for controlling the energization of said heating circuit, and means for simultaneously varying the impedances or said devices to maintain the temperature of said thermionic cathode substantially constant.

3. An electric translating circuit comprising a source of alternating current, an electric valve provided with a control grid and a thermionic cathode, a heating circuit for said cathode, a. load circuit connected to said source through said valve, an impedance phase shifting circuit energised from said source and including a variable resistor, a circuit for exciting said control grid from said phase shifting circuit, a variable resistor included in said heating circuit, and means for simultaneously varying the settings of said variable resistors to maintain the temperature of said thermionic cathode substantially constant.

4. An electric translating circuit comprising a source of current, an electric valve provided with a thermionic cathode, a heating circuit for said cathode, a load circuit connected to said source through said valve, 2. variable impedance device included in said load circuit for controlling the enorgization thereof, a variable impedance device included in said heating circuit, and means for simultaneously varying the impedances of said devices to maintain the temperature of said. thermionic cathode substantially constant.

5. An electric translating circuit comprising a source of current, an electric valve provided with a thermionic cathode, a. heating circuit for said cathode, a load circuit connected to said source through said valve, a variable resistor included in said load circuit for controlling tl'ie energization thereof, a. variable resistor connected in said heating circuit, and means for simultaneously varying the settings of resistors in an opposite sense to maintain the temperature of said thermionic cathode substantially constant.

PAUL LENZ. 

